As electronic mail message (email) usage becomes more ubiquitous, the problem generated by the volume of email received by each user increases. The problem is compounded by the ease with which not only a particular email is sent to a specific addressee, but also the relative ease with which copies of the email may be sent as “carbon copies” (cc) to other receivers. In addition, emails may not only be sent and received from a computer, but may be sent and received from other equipment such as some personal digital assistants (PDAs).
The volume of email sent is huge. In the United Kingdom alone, for instance, it is estimated that in the early part of 2008 almost three billion emails were sent every day, averaging approximately 50 for every single inhabitant of the country. Similar rates are probably true for other countries.
Consequently, any system which improves the efficiency of email delivery would be advantageous.